1. Field of the Invention
This invention relates to a lifting jack structure and more particularly to an improved lifting jack structure suitable for lifting boats.
2. Description of the Prior Art
The lifting of boats on and off wheeled carriers is a headache common to all boat users. While a variety of lifting jacks are known for both boats and automobiles none has been found that provides a simple and efficient lifting jack system usable for lifting boats on and off wheeled carriers. Some typical existing jacks may be found in U.S. Pat. Nos. 2,997,292 (boat jacks for rotating a boat on its side); 3,114,535 (boat jack for lifting a boat out of water); 3,158,354 (jack for campers); 3,159,381 (automobile jack); 3,415,490 (jack for lifting campers and trailers); 3,749,361 (airplane jack); and 3,753,550 (jack for land vehicles). The foregoing are so complicated that their use is either inefficient uneconomical, or both.